Camshaft change

desertrover · Post by **desertrover** » Thu Aug 20, 2009 2:25 pm

Many thanx for the spec, but what is the lobe center angle?
Is it more than the 108° of my 270, because someone wrote that the 108° is the prob!
And what is CCT?
I checked the carb or it was checked, this should be fine.

kiwicar · Post by **kiwicar** » Thu Aug 20, 2009 2:28 pm

Ah that explains much, I was thinking about 268 degrees total for the 3.9 cam. . . if it is 285 then it is little wonder the 272 cam is gutless in comparisn, you just want a little more lift with that timing

Mike

desertrover · Post by **desertrover** » Thu Aug 20, 2009 2:41 pm

Hi Mike,
at the moment there`s a Piper 270/108 ( old style ) with the following spex in an 4.6 with Edelbrock 500, a Mallory Unilite and 4.6 heads ( ported and slightly polished otherwise standard ) CR 9.35-1 in a LR 90 V8:
1500 - 6000 rpm; 28-64-64-28; 272°, .445", 108°

The cam I had before, was a standard 3.9 efi one, spex:
???; 32-73-70-35; 285°, .390", ??

So you think that the 3.9 I had before gives more grunt, as I understand correctly.

What figures of the cam do I have to look at for max grunt, but the engine should be flexible as well?

kiwicar · Post by **kiwicar** » Thu Aug 20, 2009 6:47 pm

For a heavy car where you want max grunt but still be able to rev it freely I would be looking at advertised duration (ie duration just off sear, not duration at .05" then about 275 to 280 inlet duration 280 to 285 on the exhaust and 112 to 114 LSA, probably timed at 108 degrees. it should give power from right down the bottom of the rev range and work well with the carb with headers and a stage 1 porting job.
That is theory not something I have used on an engine.
Mike

desertrover · Post by **desertrover** » Thu Aug 20, 2009 7:27 pm

Hi,
sounds great, but I´m not sure if in Nairobi they are able to do the job of timing in etc.
So my idea is to go back to basics ( 3.9 ).

CastleMGBV8 · Post by **CastleMGBV8** » Thu Aug 20, 2009 10:21 pm

Stephan.

I tend to agree with Mikes suggested spec as that would give good performance in your vehicle.

Looking at your current engine spec it looks very much like an RPI engine, is that the case and you bought it from them and was the Piper cam already fitted?

I really suspect that if the cam was not run in it is severly worn and will need changing anyway.

Appreciate the problem that in Nairobi you may not have mechanics who can do any specialist setting up of a cam, who would you get to do a cam and LIFTER swap.

Is there anyone who does work on American cars/engines as the Rover is just a Buick in disguise and anyone who knows about cams should know how to set one up properly and do the correct break in procedure.

If you buy a cam make sure you get one that has been machined for the cam retaining plate of the 4.6 engine.

Kevin.

desertrover · Post by **desertrover** » Thu Aug 20, 2009 11:11 pm

Hi,
no it´s not a RPI engine.
I bought a used RR block in 2002 with 20´miles on the clock and fitted all the ancilleries of my existing 3.5, including a Holley 390.
With this change, I switched to Mallory dual point. The cam I was recommended to fit by a leading Morgan tuner in Germany, was the 3.9 from a RR Classic.
A Rimmer bros sports exhaust with headers was already there ( 4-2-1 ).
After a while I fitted a Edelbrock 500.
Last year in September I fitted the oldstyle Piper 270/108 ( that I bought new on ebay some years before ) along with an unilite conversion kit for the
dizzy.
The cam was fitted as a standard cam has fitted, with the marks on the crank- and cam wheel facing each other.
We used the running in "oil" that was deliverd with the cam.
We ran the cam in ( don´t know the exact time.
All worked well, on a 1500miles trip to the french/italian alps some weeks later two. I was not very surprised with the performance, but it was ok.
On the trip to Africa the engine started pinging in Milano ( once ) and heavier in Genova. I thought that tere´s some trouble with the fuel.
CR 9.35-1, 95 octane.
In Tunisia a tried some things with the carb, and retarded the timing.
The fuel in Egypt sometimes was just 90 octane, so I used booster.
I retarded the timing some more times until the pinging was gone.
After Sudan I always drove at high altitude, at least 1500m ( 5000 feet ) and up to 4000m. The carbs settings ( needles and jets ) were never changed, so it ran very rich, as it was on the rich side in Germany ( altitude 300m ) too.
Now that I was on the last visit in Kenya and Tanzania, I came down to lower altitudes ( 800 m ) and the engine ran much better.
But it was much heavier on fuel an less torquey than in original state ( 3.9 cam ), but perhaps time made me blinde.
On a last years trip to France ( just doing around 100km/h on the french autobahn, because I was following a friend with a trailer ) I managed to do 15-16l per 100 kms.
In Kenya I was driving 110 km/h sometimes on tarmac road ( average 75 km/h on tarmac roads ), but the most was light offroading on sandy tracks with 40-60 km/h. But fuel consumption was at least 22l/100kms.
OK the car now is much heavier than on the frech trip.
I don`t know what to do.
Change the cam now ( in Nairobi ) or wait until I´m getting to lower altitudes in Malawi to Namiba, check it than again and perhaps change the cam in Namibia ( with German technicians knowledge ).

topcatcustom · Post by **topcatcustom** » Fri Aug 21, 2009 7:13 am

CastleMGBV8 wrote: If you buy a cam make sure you get one that has been machined for the cam retaining plate of the 4.6 engine.

Kevin, dont forget that the 4.0 and 4.6 engines have different cams and dont have dissy drive gear, and the retaining plate is actually a horseshoe type that runs in a grove in the extra wide front cam support.

CastleMGBV8 · Post by **CastleMGBV8** » Fri Aug 21, 2009 9:50 am

Tom,

Stepahan has a 4.6 engine with the earlier 3.5 front cover with a dizzy.

I was suggesting that whatever cam he chose to make sure it was machined for the cam retainer plate.

Stephan ,

Yes I understand your difficulties, if there is no one you can trust to do the relatively simple work locally then it seems you will have to wait until you can take it the German garage.

There are several high torque cams on the market and the 4.6 engine is designed because of it's long 82mm stroke to be a high torque engine anyway.

I'll have a look at whats available, as some of these may be fittable in the standard timing positions.

Whichever cam you decide on the breaking in procedure MUST be done correctly otherwise the cam could be useless within 500 miles.

The fuel problem is certainly hurting performance and having to back off the timing to avoid detonation is costing you a lot of power, lower compression and correct timing would probably give better results, one answer would be to fit thicker Cometic head gaskets to try and get the C/R down to about 8.5/1

Also if you are running with the vacuum advance connected try disconnecting it as the Edelbrock can provide too much vacuum but as you have the mallory alternatively set the vacuum advance to no more than 5 degrees and reset the initial advance to 6 degrees and this may just transform the performance, I would try this before doing anything else as you may be surprised by the results.

There are some AA 3 spanner rated garages on this list might be worth having a talk with and ask them what procedure they would use for changing a cam to see if they know what there talking about.

http://www.aakenya.co.ke/agents.htm

Kevin.

kiwicar · Post by **kiwicar** » Fri Aug 21, 2009 3:42 pm

Hi Stephen
Just noticed in you previous post
LCA is lobe centre angle, it is the angle between the centre lines of the two cam lobes (inlet and exhaust) measured in camshaft degrees, not crank rotation degrees also called LSA lobe seperation angle, and it dictates the amount of overlap for the inlet and exhaust for a given duration.
CCT is an abreviation for circuit which is a word I can't spell without a spell checker (along with many others as you will have noticed by now!) so tend to use this instead.

Best regards
Mike

desertrover · Post by **desertrover** » Fri Aug 21, 2009 7:12 pm

Ian Anderson · Post by **Ian Anderson** » Sat Aug 22, 2009 8:02 am

desertrover wrote:Hi,
sounds great, but I´m not sure if in Nairobi they are able to do the job of timing in etc.
So my idea is to go back to basics ( 3.9 ).

I come originally from Rhodesia / Zimbabwe
Out in Africa everything has several lives - even simple plastic milk bottles end up being used to carry water in rural areas, cars are never "written off" if they can be fixed etc

So I would presume that an engineering company in Africa could certainly put together and correctly put together a Rover V8 motor.
It may take a while phoning around to get the best one recomended but I'd be certain that the job you get done will be good and probably at half the price of a similar job in europe

Ian

Rage Rover · Post by **Rage Rover** » Thu Oct 15, 2009 12:31 pm

Just read this thread and I have my own very similar experiences to share .
I have a 3.5 with Webber 500 , stage 1 heads , 9.35 CR , mallory unilite , 4 branch manifolds and all that good stuff. I also have the piper cam which i am assuming is an old one and it is fitted to a land rover offroader .
The car idles well and makes reasonable power off idle , unfortunetely it's into the doldrums by 1600 rpm . At 3 grand it really goes banzai - like flicking a switch . Most of the time my cruise rpm is around 2000 rpm to 2,500 rpm so i'm always changing down if there is a decent hill coming up .
I've tried everything , timing , changing the unilite springs , messing with the carb needles to no avail . My last V8 was completely unmolested and would go really well on twin SU's . My own thoughts are to go to a 3.9 Rangie cam and leave all this cam nonsense behind

desertrover · Post by **desertrover** » Thu Oct 15, 2009 1:09 pm

That´s what is on the way down in Nairobi at www.schuhmacher4x4.com .
They change the cam to the 3.9 cam and I think I´m satisfied again!!

CastleMGBV8 · Post by **CastleMGBV8** » Thu Oct 15, 2009 11:17 pm

Don't forget to fit new lifters with the new cam and use the special lube and run it for 20 mins at 2000 - 2500 RPM without letting it idle, if it get too hot then shut it down and run again once it's cooled down, others have suggested spraying the rad with cold water helps keep it cool.

Kevin.